The present invention concerns silicone rubber compositions for treatment of fiber structures, such as woven fabric, knit fabric, nonwoven fabric, etc. More specifically, the present invention relates to silicone rubber compositions for treatment of fiber structures, having long pot life and imparting films of excellent tensile strength, tear strength, and abrasion resistance.
Fiber structures, such as woven fabrics, knit fabrics and nonwoven fabrics, treated (especially coated) with conventional silicone rubbers are soft with excellent water-repellency, water-pressure resistance and also high moisture permeability. Thus they have been widely used in diaper covers, snow wear, mountain wear, sports wear, raincoats, tents, etc.
The silicone rubbers used for coating fiber structures are, e.g., addition reaction-curable silicone rubbers (Japanese Kokai Patents Nos. Sho 58(1983)-171937, Sho 60(1985)-51754 and Sho 57(1982)-165069) and condensation reaction-curable silicone rubber (Japanese Kokai Patent No. Sho 53(1978)-94693).
However, the silicone rubbers have some strong points and also some weak points, and both long pot life and desirable physical properties cannot be obtained at the same time.
For example, addition reaction-curable silicone rubbers form films with good tensile strength, tear strength, abrasion resistance, etc., while their adhesion to fiber structure is weak, and curing may be adversely affected by small amounts of surfactants and other impurities of phosphorus, nitrogen, sulfur compounds adhered to the fiber during processing of fibers or fabrics.
On the other hand, the condensation reaction-curable silicone rubbers show good adhesion to the fiber structure, while tensile strength, tear strength and abrasion resistance are not sufficient.
In the case of condensation reaction-curable silicone rubbers based on hydroxy-terminated organopolysiloxanes and organohydrogenpolysiloxanes, such drawbacks may be overcome by compounding inorganic reinforcing fillers such as finely powdered silica; while with increasing silica content, pot life decreases, and gelation occurs within 30 minutes, thus coating workability is poor.